(1) Field of the Invention
This invention relates, in general, to fire extinguishing sprinkler heads, and, in particular, to an improved, automatic sprinkler head that can be mounted substantially flush with the ceiling of a fire protected enclosure.
(2) Description of the Prior Art
Sprinkler systems are used extensively to provide automatic fire protection for residential, commercial and public buildings. A sprinkler head to qualify as suitable for use in a residential sprinkler system must pass many tests, several of which go beyond those normally used for ordinary commercial/industrial type sprinkler heads. The two greatest distinctions between such ordinary, and residential-type, sprinkler heads are the operating speed and specially designed water spray patterns that fire tests have revealed are necessary to combat or extinguish a fire in typical residences. The residential type sprinkler head must operate at a faster speed than the ordinary commercial/industrial sprinkler head, the faster the better, as the protection of human life in involved. Thus, there is a keen interest in providing residential sprinkler heads with ever shorter times to become operable.
In residential dwellings, moreover, and sometimes even in commercial buildings, it is most desirable to utilize a sprinkler head that can be located almost entirely above the ceiling so as to be hidden, or concealed, from view, leaving the attractiveness of a room relatively unspoiled.
Exemplary of prior Art showing concealed fire sprinkler heads are U.S. Pat. Nos. 3,633,676; 3,756,321; 4,015,665; 4,105,076; 4,465,141; 4,491,182 and 4,508,175.
The automatic fire sprinkler head, whether of the commercial/industrial type or one for residential dwellings, comprises, in general, an elongated body member which is open at one end, and connected to a pressurized fire extinguishing fluid, e.g. water, and is closed at the other end by a valve assembly, or mechanism which operates to open the valve in response to a fire. The valve body member ordinarily is maintained in the closed position by the assembly, in part, by a low melting point fusible composition, until the occurrence of a fire. With such an occurrence, when the ambient temperature rises to a predetermined level, the fusible composition melts, resulting in the valve mechanism operating to open the valve, i.e., move the valve body member from the closed position to the open position, thereby allowing the discharge of the fire extinguishing fluid onto the fire.
Of the above disclosed patents, U.S. Pat. Nos. 4,491,182 and 4,508,175 both disclose the fusible element contained in the bottom of what might be termed an open-top cylindrical container, or "housing", as disclosed in U.S. Pat. No. 4,508,175. Heat is supplied to the fusible composition, in both cases, by one or more circular-shaped heat collecting fins carried by the housing. In U.S. Pat. No. 4,508,175 there is disclosed, moreover, an insulating disc resting on top of the heat fusible composition, which along with the insulating ring separating the housing from the sleeve holding it, apparently confines the heat collected by the fins, to the housing, whereby that heat, rather than being dissipated to other parts of the valve assembly is directed to the melting of the heat fusible material.